Graphite and/or carbon disk with removable wear faces

ABSTRACT

The invention comprises a brake disk assembly in the form of a carbon or graphite disk which is provided on both sides with thin wear plates of carbon or graphite material. The plates are either in segmented or full circle form and are secured to the core by rivets and bushings which also secure the keyway drives of the disks.

United States Patent 11 1 [111 3,800,392 Cook et al. Apr. 2, 1974 [54]GRAPHITE AND/OR CARBON DISK WITH 2,655,237 10/1953 Benson l88/7l.6 XREMOVABLE WEAR FACES 2,902,130 9/1959 Halberg 6! al. 188/73.2 3,480,11511/1969 Lallemant 1 188/71.5 [75] Inventor Alb rt W- C k, T g J p3,552,533 1/1971 Nitz et a1. 188/251 A x F. Dernovshek, Akron, both ofOhio 3,650,357 3/1972 Nelson et al 188/71.5 [73] Assignee: The GoodyearTire & Rubber Company Akron Ohm Primary ExaminerGeorge E. A. Halvosa[22] Filed: Oct. 20, 1972 Attorney, Agent, or FirmF. W. Brunner; P. E.Milli- 211 App]. No.: 299,369 O'dham Related US. Application Data [62]Division of Ser. No. 87,126, Nov. 5, 1970, Pat. No.

3,712,427. [57] ABSTRACT [52] 11.8. CI. 29/401, 188/73.2, 188/218 XL,The invention comprises a brake disk assembly in the 192/70.13, 192/107R form of a carbon or graphite disk which is provided on [51] Int. ClB22d 19/10 both sides with thin wear plates of carbon or graphite [58]Field of Search l88/73.2, 218 XL; material. The plates are either insegmented or full cir- 192/107 R, 70.13; 29/401 cle form and are securedto the core by rivets and bushings which also secure the keyway drivesof the {56] References Cited disks.

UNITED STATES PATENTS 2,594,810 4/1952 Schaub et al. 29/401 1 Claim, 6Drawing Figures PATENTED 2 I974 SHEET 1 [IF 2 22 FIG-2 F l G.- 3

1 GRAPHITE AND/OR CARBON DISK WITH REMOVABLE WEAR FACES This applicationis a divisional application of Ser. No. 87,126, filed Nov. 5, 1970, nowUS. Pat. No. 3,712,427. I

This invention relates to brake assemblies of the type having alternaterotating and stationary brake disks carried between and axially movablebetween a backing plate and a pressure plate. More particularly, theinvention relates to an improved brake disk for use in such an assembly.

With carbon or graphite brake disks of the prior art the entire assemblymust be'discarded when the surfaces of the disk have become sufficientlyworn. This, however, involves the discarding of a disk which is stillstructurally sound, and the replacement with a new assembly is extremelyexpensive.

It is the primary object of the invention to provide a graphite orcarbon brake disk in which the wear surfaces of the disk may be renewedor refurbished without requiring the discarding of the entire assembly,thus realizing a considerable cost saving in replacement over the priorart disk assemblies.

In the present invention this object is achieved by providing on acarbon or graphite disk core renewable wear surface disks which may beof the same material as the core which aremechanically secured to thecore and which may be provided for a worn disk, replaced themselves, asnecessary, and'all without requiring the discarding of the entire basedisk assembly. The wear surfaces are secured by the bushings and rivetswhich hold the keyway drives to the disks.

A further object of the invention is to provide a method toeffect-refurbishment so that disks can have great longevity, andreplacement can be made at minimum cost.

For a more complete understanding of the invention and of the objectsand advantages thereof, reference should be had to the followingspecification and the accompanying drawings wherein there is shown apreferred embodiment of the invention.

In the drawing:

FIG 1 is a fragmentary side elevational view of a brake-disk constructedin accordance with the present invention, the disc shown being arotating disk;

FIGS. 2 and 3 are fragmentary sectional views taken along the lines 2-2and 33, respectively, of FIG. 1 and showing the arrangement by which thewear plates are attached to the disk core; and

FIGS. 4, 5 and 6 represent the method of refurbishment of a new soliddisk for the first, second, and third refurbishment, respectively.

The reference numeral 10 designates generally a brake diskwhich is inthe form of an annular ring and which. is provided at uniformly spacedintervals on its outer circumference with slots 12. Keyway drives 14 aresecured to the annular disk at each of the slots 12 and held in place byrivets 16. Each of the keyway drives 14 includes a notch 18 forreceiving the splines or keys of a rotating wheel assembly so that thedisks are rotated with the wheel while being capable of axial movementrelative to the wheel.

As is shown in FIGS. 2 and 3, the disk 10 is formed of a core disk 20which is of a graphite or carbon base material and of wear plates 22 oneach face of the core 20. The wear plates 22 may be of the same graphiteor carbon base material as the core plate 20 and may be either in theform of annular rings of the same size as the core 20 or in the form ofsegmented rings each forming a part of the annular ring. The wear plates22 may, however, be of a graphite or carbon base designed to providegreater frictional and heat sink capabilities, but not as great astructural capability as the core plate 20. Preferably, the core plate20 will have good resistance to oxidation and great structural strength.The core plate 20 should be a minimum of l A. times the thickness ofeach respective wear plate 22. The wear plates 22 may be full circleorsegmented as long as the segments are secured at both ends by rivetsor other appropriate means. In either event, the wear plates 22 aremechanically secured to the core 20 by means of the rivets 16 whichsecure the keyway drives 14 in place. The rivets 16 are not positionedwithin the rubbed face of the plates 22 and hence the plates 22 may bequite thin. Bushings 24 are provided on the rivets 16 to uniformlydistribute the forces between the wear plates 22 and the core plate 20.The wear plates 22 may, for example, be of from 0.075 to 0.175 inchesthick. The overall thickness of the disk assembly may typically bebetween 0.400 and 0.600 inches.

When the -wear plates 22 become sufficiently worn that they must bereplaced, it is merely necessary to remove the rivets 16, the bushings24 and the keyway drives 14. The worn wear plates 22 are .now discardedand new wear plates placed on either side of the core 20. The keywaydrives 14 are again riveted in place withthe bushings 24 and the rivets16 thus securing the new wear plates 22 to the core 20. The brake disk10 is thus renewed and capable of being reused. Since the wear plates 22are relatively thin only a small amount of carbon or graphite materialis actually discarded, the core 20 which forms the bulk disk beingreused.

It should be understood that while the disk illustrated and describedabove is a rotating disk having the keyway drives 14 and keyway slots 18on its outer circumference, the principles of the invention may be asadvantageously employed in a stationary brake disk, or one in which thekeyway drives and keyway slots are provided along the innercircumference of the disk.

The method of the invention includes a way to refurbish carbon disksincluding the pressure and end plates. The low coefficient of thermalexpansion and other desirable properties such as the high heat transfercoefficient make a carbon base material ideal from this standpoint. Byrefurbish, it is meant to take an initial solid carbon disk, andrefurbish it according to the techniques defined hereinafter. Thetechnical feasibility of refurbishing has been proved by laboratorydynamic brake testing. Specifically, after the disks went through aspecified brake life, they were refurbished and run through a requireddynamic brake test the second time to determine if the samecharacteristics were present.

FIGS. 4, 5, and 6 represent the refurbishment cycle which is believed torepresent the optimum procedure. The first refurbishment is illustratedin FIG. 4 which shows in view A a brake disk indicated by numeral 50which has been form about 0.060 so that for a rotating disk it wouldhave a thickness of about 0.480 inches and for a stationary disk about0.520 inches. The refurbishment technique in its first step willconstitute grinding both faces of the disk 50 enough to smooth it andprovide parallel opposite surfaces, or about 0.030 so that for arotating diskthe thickness would be approximately 0.450 inches and for astationary disk the thickness would be about 0.490 inches. The initialthickness is then achieved by refurbishing with a carbon plate or disk52 as indicated in view C of HG. 4 that is approximately 0.150 inches inthickness to thereby increase the overall disk thickness by that amount,hence bringing the total disk thickness up to the desired pre-worncondition. The plate 52 is attached in the manner as illustrated inFIGS. 1 through 3, but is attached only on one side as indicated in viewC of the FIG. 4.

When the disk 50 and plate 52 have again worn as indicated in view A ofFIG. 5 to approximately the same thickness dimensions as in view A ofFIG. 4, both the disk 50 and plate 52 are ground to the dimensionsindicated in view B, with a new plate 54 being added as in view C tocomplete the refurbishing of the disk and the return to its initialthickness dimensions. Note, however, that plate 52 is only approximatelyone-half the thickness of plate 54. This completes the secondrefurbishing with a structure which now has two wear plates 52 and 54 ofdifferent thickness configurations.

The third refurbishment and all subsequent refurbishments areillustrated in FIG. 6 where view A illustrates the worn disk 50 andplates 52 and 54. View B illustrates the grinding of plate 54 while viewC illustrates the positioning of a new plate 56 in combination withplate 54 to achieve the complete refurbishing. In this instance, plate52 has been discarded because it has worn to such a thin thickness thatit is no longer structurally usable. Note, however, that the base disk50 remains at the same thickness during the third refurbishment and, ofcourse, for all refurbishments thereafter.

While in accordance with the Patent Statutes, only the best knownembodiment of the invention has been described and illustrated in detailit will be understood that the invention is not so limited. Referenceshould therefore be had to the appended claims in determining the truescope of the invention.

What is claimed is:

l. A method for refurbishing a worn brake disk assembly comprising anannular core of a carbon base material having a plurality of keywaydrives separate and independent from said core secured at uniformlyspaced intervals on one circumference of the core which comprises thefollowing steps:

1. removing said keyway drives from the core,

2. grinding down the worn opposite surfaces of the core to a smoothparallel configuration;

3. placing a plate of substantially the same material as the core but ofless thickness fully covering one of the sides thereof;

4. adding a second plate of the same material as the core and the firstthin plate to the other side of the disk; and

5. securing the keyway drives, thin plates, and annular core as a unit,which core and both plates in combination provide a desired thickness.

1. A method for refurbishing a worn brake disk assembly comprising anannular core of a carbon base material having a plurality of keywaydrives separate and independent from said core secured at uniformlyspaced intervals on one circumference of the core which comprises thefollowing steps:
 1. removing said keyway drives from the core, 2.grinding down the worn opposite surfaces of the core to a smoothparallel configuration;
 3. placing a plate of substantially the samematerial as the core but of less thickness fully covering one of thesides thereof;
 4. adding a second plate of the same material as the coreand the first thin plate to the other side of the disk; and
 5. securingthe keyway drives, thin plates, and annular core as a unit, which coreand both plates in combination provide a desired thickness.
 2. grindingdown the worn opposite surfaces of the core to a smooth parallelconfiguration;
 3. placing a plate of substantially the same material asthe core but of less thickness fully covering one of the sides thereof;4. adding a second plate of the same material as the core and the firstthin plate to the other side of the disk; and
 5. securing the keywaydrives, thin plates, and annular core as a unit, which core and bothplates in combination provide a desired thickness.